VIX® futures are settled in cash on the Wednesday that is 30 days prior to the next month's standard S&P 500 Stock Index (SPX) options expiration date, which is the 3rd Friday of the next month.
Specific expiration dates may be found within the Expiration Calendar.
Last trading day is the Tuesday prior to settlement day at 3:15 CT. They are then settled in cash based on a special VIX index calculation. The special VIX index calculation uses actual opening trades in SPX options. This is a "special calculation," because the VIX index calculated throughout the day is based on the mid-point of the bid - ask spread of SPX options.
The final VIX index settlement level on expiration Wednesdays is disseminated under the symbol VRO.